Production of dibenzanthrone



I are by weight.

Patented July 28, 1931 UNITED STATES:

P N jOFF E a HANS J'OSEF EMMER, or MANNHEIm GERMAux, nssiGNoIp T0, eE Nnaen gimme WORKS, INC., or NEW YORK, 11. Y., A' CORPOR'ATION or DELAWARE PRODUCTION OF DIBENZANTHROIN'E No Drawing. Application filed May 23, 1928, Serial No. 280,122, and in Germany-June 23, 1927.

compounds of sulfoxylic acid and sulfurous acid, as for example, sodium-formaldehyde sulfoxylate, zinc-formaldehyde sulfoxylate,

zinc-acetaldehyde sulfoxylate, sodium-for maldehyde-bisulfite, sodium-glyoxal bisulfite, sodium-benzaldehyde-bisulphite and the like. The increased yield, generally speaking, is accompanied by improved purity of the crude dyestufi'. j The following examples will further illustrate the nature of the said invention, which however is not restricted thereto. The parts Ewample 1 treatment being that already known and usually adopted. I

' Example 2 I A mixture of 100 arts of crude benzanthrone-and 20 parts 0 sodium-formaldehydebisulfite is uniformly introduced in the. course of an hour, assiste by stirring, into a melt of 200' parts of per cent caustic potash and 14 parts of anhydrous sodium acetate at a temperature of about 205 to 210 0., the

to 225 C. and the stirring continued at that temperature for about 1 to 1 hours longer. The subsequent treatment is carried out in the manner already known and usually adopted.

The sodium-formaldehyde-bisulfite may be replaced bythe bisulfite compounds'of other aldehydes, such as sodium-glyoxal bisulfite, sodium-benzaldehyde-bisulfite and the like.

Ewample 3 A mixture of parts of crude benzanthrone and 20 parts of sodium-formaldehydesulfoxylate is uniformly introduced, while stirring, in the course of an hour, into a melt of 200 parts of 90 per cent caustic potash and temperature being then raised to about 220 14 parts of anhydrous sodium acetate at a temperature of about 200 to210 (1., the temperature being then raised to 220 to 225 C. and stirring continued at thattemperature for a further 2 hours. Thesubsequent treatment is carried out in the manner already known and usually adopted.

Similar action to that of sodiumformaldehyde 'sulfoxylate is exerted by other aldehyde'compounds of sulphoxylic acid, such for example as zinc-formaldehyde sulfoxylate,

zinc-acetaldehyde suli'oxylate and the like.

What I claim is 1. A process for the production of diben- V zanthrone which consists in treating benzanthrone with fused caustic alkali in the 1 presence of a compound selected from the group consisting of aldehydes, their polymerization products and substances yielding aldehydes,,under the conditions of workin 2. A process for the production of di enzanthrone which consists in treatin benzanthrone with fused caustic alkali in the presence of a com ound selected from the group consisting o formaldehyde, its polymerization products and substances yielding formaldehyde under the conditions of Workmg.

3. A process for the production of dibenzanthrone Which consists in treating benzanthrone with fused caustic alkali in the presence of a compound selected from the group consisting of formaldehyde bisulfites and formaldehyde sulfoxylates.

4. A process for the producing of dibenzanthrone Which comprises treating benzanthrone with fused caustic alkali in the presence of sodium formaldehyde sulfoxylate.

In testimony whereof I have hereunto set In hand.

y HANS JOSEF EMMER. 

